Inflatable rubber bladders are used in machines for assembling, forming and curing pneumatic tires. These bladders are typically made from isobutylene rubbers especially when used at higher temperatures such as from 100.degree. to 150.degree. C. Isobutylene polymers are preferred over diene based polymers because they are inherently more resistant to oxidation at the above-recited cure temperatures typically used and often required for forming tires. This is because of the relatively low levels residual unsaturation available for crosslinking isobutylene polymers (butyl rubber) compared to diene-based polymers. Adhesion of the cured tires to the rubber bladders is generally avoided by applying a liquid silicone-based lubricant either to the bladder or the tire components that are to be in contact with the bladder.
The need to apply a lubricant (also called dope) to the bladder tire interface slows the tire manufacturing process. Lubricants as used herein define liquids that do not crosslink under the conditions used to cure tires (i.e., 100.degree.-180.degree. C.). Excessive lubricant or the transfer of lubricant can discolor the tires or contaminate other surfaces where bonding is desired. Insufficient lubricant results in bonding of the bladder to the tire at the tire-bladder interface. When this interface bond is broken or torn when removing the cured tire, this can cause defects in the tire, roughens the bladder surface, or can promote bladder failure.
Bladders are used in curing presses to press the tread and sidewall regions of the tire outwardly against the mold surface during tire manufacturing. These bladders are filled with a heated fluid (preferably steam) to help speed the curing process of the tire. The high potential elongation of the bladder or sleeve (i.e. greater than 300 percent) allows the bladder to stretch and conform during tire curing and allows the bladder to stretch while tearing away from the molded tire.
Other inflatable bladders and sleeves have found uses in other rubber forming and curing processes. These similarly suffer from the necessity of supplying a lubricant at the interface between the bladder and the hydrocarbon component to be cured.